The present invention relates to a contact arrangement for detachably attaching an electrical component having a plurality of terminal contacts, for example an integrated circuit of the BGA-type (ball grid array), of the CGA-type (column grid array), of the LGA-type (land grid array) or of the flip-chip type, to a printed circuit board, having a number of electrically conductive contact pins which are directly attachable to the printed circuit board, and which, attached state, extend away from the printed circuit board at approximately right angles, each of the contact pins being connected to at least one conductor path of the printed circuit board for establishing an electrical connection. The present invention further relates to the board-to-board correction between two printed circuit boards.
The technologies and processes for producing integrated circuits have been constantly improved in the last few years. There is no end in sight of the technical advance in this field. The constant further developments have led to the integrated circuits becoming increasingly larger and more complex. Starting from single electronic basic components integrated on a chip, such as transistors, diodes, resistors, etc., integrated circuits have been fabricated which contain countless thousands of basic components. A great problem that had to be solved with the increase in complexity of the integrated circuits, and must be newly solved or improved again and again, is the leading-out of the electrical terminals. The number of such terminals has become no longer limited to just a few but today may easily already be provided in a plurality on the order of magnitude of over 600.
Such LSI circuits, for example arithmetic units in computer technology, may also be considerably expensive. Connector blocks have therefore been created which are soldered to the conductor paths of a printed circuit board instead of the integrated circuit. A connector block has contact arrangements formed in such a way that an integrated be pluggably connected to the connector block. In this way, the highly complex integrated circuit is exchangeable at any time. In particular, when replacing such an integrated circuit having very many terminals, one does not run the risk of destroying the conductor paths of the printed circuit board with the multitude of other electronic components disposed thereon, through a desoldering operation which is not easy to accomplish because of the many terminals. There are integrated circuits formed substantially as rectangular plates. On a typical one of these, the electrical terminals are disposed along the side surfaces of the plate. Such integrated circuits can be plugged into a frame-shaped connector block. There, there is a spring contact-lug for each terminal of the integrated circuit. This kind of connector block is provided for the mounting of integrated circuits corresponding to the PLCC construction form.
In another type of highly complex integrated circuits, their terminals are led out in pin form on the underside of the housing. These are integrated circuits with terminals disposed in a so-called pin grid array (PGA). Connector blocks for these provide contact pins disposed in a plastic slab corresponding to the grid of the terminal pins of the integrated circuit. The contact pins are essentially formed as jacks which on one side can be plugged into a hole mask on the printed circuit board and soldered to the conductor paths there and on the other side have contact springs inside each jack for ensuring a faultless electrical contact with the contact pin to be received.
These two kinds of connector blocks have the disadvantage that particularly in the case of integrated circuits having very many electric terminals, considerable force must be expended for inserting the integrated circuit in the connector block and for removing the circuit from the connector block. The danger that the integrated circuit is destroyed as a result is not negligible.
Nor is it particularly easy, furthermore, especially with the second-mentioned type of known connector block, to center on the contact pins an integrated circuit to be inserted. It occurs relatively frequently that in the case of poor centering, terminal pins of the integrated circuit are bent over and break off when straightened.
The design of the LSI circuits has likewise been adapted to the art of surface mounting technology (SMT). Thus, for this purpose, the terminals of an integrated circuit disposed in a grid array, for example, have no longer been made pin-shaped but have been made substantially spherical-segment-shaped. To that end instead of a pin, there protrudes from the underside of the housing of the integrated circuit for each terminal a part-spherically curved segment, preferably, a hemisphere. The terminal arrangement of thus integrated circuits is known by the term ball grid array (BGA). The dome-shaped terminals of such integrated circuits, during attachment of the latter to a printed circuit board, are soldered directly to contact areas of the printed circuit board. In case of subsequently perceived non-functioning or faulty functioning of a thus attached integrated circuit, the latter can be removed and replaced by another integrated circuit only with very great expenditure and with the constant danger of destroying the printed circuit board. The failure rate of printed circuit boards which can then no longer be used through such an operation is correspondingly great.